Surgical instrumentation often uses fiber optics to direct light from a light source, such as a laser, LED or other light source, to a surgical hand piece. The tip of the surgical hand piece is then used to direct the light to the eye. In some cases, it is desirable to attenuate the brightness of the light received at the eye. Currently, position domain attenuators that proportionally interrupt part, or all, of a light beam are used. In these systems, a non-optically transmissive element is positioned to prevent a part of the light beam from reaching the target fiber, resulting in some attenuation. Position domain attenuators include rotating louvers, variable slot width obstructions, varying aperture size obstructions and varying neutral density filters. By obstructing just a portion of the light beam, the quality of the illuminated spot projected from the end of the fiber can be affected. For example, the projected spot on the eye may have a bright center from the light that is not obstructed as well as shadow and color rings from the light that was obstructed. Indeed, the center of the spot may exhibit no attenuation, while the edges of the spot are highly attenuated. This result can be undesirable as it provides an uneven energy distribution to the eye.
Another current attenuation approach includes adjusting the voltage or current of the light source, thereby changing the intensity of the produced light. While this approach can evenly attenuate the brightness of the light spot received at the eye, it suffers the shortcoming that the color temperature of the light is typically changed.